I can't see how the
temperature of the water on the stainer could be causing this artefact as the
problem tends to be intermittent even when batch staining.

Sometimes within a
rack of slides you will get some slides from GI biopsies showing the artefact
while others from the same clinic session do not.

It has to be something
individual to each specimen in my opinion, otherwise we would see every slide
going through on that particular batch exhibiting the same staining artefact,
which we don't.

I still think the
actual biopsy process has a major part to play, especially as that's the only
variable we don't have any control over and all the others we
do.

The temperature thing
is a spurious argument in my opinion when you consider all blocks are chilled
prior to cutting so everything is cold at some point and if you do immuno
antigen retrieval you apply excessive heat to the slide and still get good
nuclear detail when the section is counterstained.